1. Field of the Invention
The present invention relates to a method for manufacturing a thin film, and more particularly, to a method for manufacturing a thin film by atomic layer deposition (ALD).
2. Description of the Related Art
A thin film is typically used for a dielectric of a semiconductor device, a transparent conductor of a liquid-crystal display, or a protective layer of an electroluminescent thin film display. The thin film is formed through evaporation, chemical vapor deposition or ALD.
ALD is a surface controlled process, and uses two dimensional layer by layer deposition. In the ALD method, the deposition is performed in a surface kinetic regime. Thus, the step coverage is excellent. Also, a reactant is decomposed through chemical exchange by periodically supplying the reactant without pyrolysis so that the resultant film has high density and precise stoichiometry. Also, by-products generated by the chemical exchange are gasses that can be easily removed. Accordingly, so a chamber can be easily cleaned. The temperature is the only process variable in the ALD method, so the process is easily controlled and maintained.
However, in the conventional ALD, since enough reactant is not adsorbed on the surface of a substrate, a defect such as a pinhole is generated in the thin film. Therefore, the physical characteristics of the thin film, such as the film density, deteriorate. Also, in the conventional ALD, since a chemical ligand is not substantially removed, it is not possible to obtain a precise stoichiometric thin film.